The present invention relates to an azimuth adjusting device for a magnetic head. The device can carry out azimuth adjustment of the magnetic head with high precision.
In tape recorders and the like, the inclination of a magnetic head relative to the tape, i.e., azimuth adjustment, is most important to obtain recording or reproduction of good quality.
Particularly, in present day super-miniature tape recorders, in order to obtain long recording times, the tape speed is set extremely slow. Thus, in order to improve recording density for carrying out recording and reproduction of good quality with the slow moving tape, it becomes all the more important to make the azimuth adjustment error extremely small.
In conventional azimuth adjusting devices, as shown in FIGS. 1a and 1b, the inclination of a head fitting plate 5 which supports a magnetic head 4 is adjusted by a pair of adjusting screws 2, 3 threaded in a substrate 1. That is, FIG. 1a shows that when one screw 2 is fixed and the other screw 3 is rotated, the inclination of the head fitting plate 5 is adjusted and an azimuth error .theta..sub.1 of the head 4 is eliminated.
However, such construction cannot provide an azimuth adjustment of high precision for the reasons mentioned below.
That is, .theta..sub.1 in case of an output 0 by an azimuth displacement is expressed by EQU tan.theta..sub.1 =.lambda./W (1)
wherein a recording wavelength is .lambda. and the track width of a tape is W.
In this case, the inclination of the head fitting plate 5 is equal to .theta..sub.1, so that if a distance between the adjusting screws 2 and 3 is l and a height error caused by the inclination of the head plate 5 is S, the following is obtained. EQU tan.theta..sub.1 =S/l (2)
Here, if the pitch of the adjusting screw 3 is P, and the rotational angle is .theta..sub.2, it is expressed by S=.theta..sub.2 P, so that from the equations (1) and (2), the following equation is obtained. EQU .lambda./W=.theta..sub.2 P/l (3)
Therefore, as apparent from the equation (3), in order to heighten the precision of the azimuth adjustment, it is preferable to make the distance l between the adjusting screws 2 and 3, i.e., the length of the head fitting plate 5, relatively large, or the pitch P of the adjusting screw 3 small. However, in actual super-miniature tape recorders, it is impossible to take sufficiently large space for the length of the head fitting plate 5, and there is also a limit to the extent the pitch P can be made small because of the dimensions of the screw.
As a result, if the recording wavelength .lambda. is made small for the purpose of increasing the recording density, the adjusting precision of the azimuth is largely controlled by the precision of adjustment of the rotational angle .theta..sub.2 of the adjusting screw 3, since the track width W is constant.
However, in the construction shown in FIGS. 1a and 1b, the adjusting screw 3 is directly rotated to adjust the azimuth error, so that high precision can hardly be expected through adjustment of the rotational angle .theta..sub.2 of the screw 3.